Just FYI from my experience. If you see a tool with 3 phase motor and do not have 3 phase power you may consider building yourself a 3 phase rotary converter (obviously, you could buy one if you have the money).
I just built one which will start a 5 to 7 HP motor and service upto 20 HP of multi motor application load.
Followin gis what you would need to build one:
Magnetic motor starter: My 7HP variety cost $75 for a used one comes with thermal overload protection. BTW, most of the commercially sold converters do not provide this and expect you to add it or use your circuit breaker as a switch.
Couple of relays: Bought new for $35
Start and Run Capacitors: Bought new for $100
A 3 phase idle motor: Bought 10 HP used one for $140
Add another $50 for enclosure and wiring.
So for about $400 you can build this thing.
To run your 3 phase tool you flip a switch to start your converter and then start your machine.
If there is interest in my plans post a response.
Imran
Replies
I am in a similar situation three phase motors but no three phase power. I have been waffling between changing out motors or buying a rotary phase converter. The converter I am looking at is made by Ronk and is about $400 also but the capacity is not as great as your setup. I have been thinking that it would be easier and less expensive to change out the motors. The only advantage to staying with the three phase motors would be if you needed to start the motor under load, as far as I can think of this is never the case with woodworking.
Is anyone aware of any other reason to stick with the three phase power if you can get single phase motors that will replace the three phase motors ?
Michael Blutt
The biggest one. A new tablesaw motor, 3 to 5 hp, will cost you as much or more than the converter (single-phase is generally more costly to buy than equivalent poly-phase), plus motors for other tools you may be changing. Plus there are more parts to break in all those single-phase motors (a relatively small concern for home users). Unless you're running more than one tool at a time, you only need enough power for the heaviest load. And once you have the converter, you can take advantage of other used 3-phase tools that home shop folks won't touch; they generally sell for less. Look on ebay for what 3-phase saws go for compared to the same thing in single-phase. I could think of several more reasons, but you get my point.
Be seeing you...
Michael,This is a more complex subject than can be covered here but a good reason for not changing the motor on a machine that could be changed is to add infinitely variable speed such as a drill press, shaper, bridgeport (ok...not really woodworking) by using an inverter. An inverter gives full power, reverse, and can even double the motors rated speed. On a hp or less I can get a unit that will run off of 110 volts instead of 220 volts, perfect for a drill press
As far as rotary phase converters you can save time by buying a static converter and hooking up a slave motor. There's a lot of other ways to do this as well. There's a few other sites that go into more detail on options.
Rick,
I agree that it would be easiest to buy a static converter and add the 3 phase idler/slave motor and the run capacitors to balance the phase voltages. The problem I faced is that a good static converter (GMW or GWM) was $329. The static converter can be build with a start/stop push button and cheap electrolytic caps. In my setup 900uF of electrolytic caps cost $30 and 170uF of run caps cost $80.
Imran.
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